Radial and axial airflow fan

ABSTRACT

The open forward unobstructed root portions of radially extending fan blades are secured to the arms of front and rear portions spaced apart axially. A large aperture in the central portion of the front spider enables air to flow axially into a chamber between the front and rear spiders which opens radially outwardly between the root portions of the blades. Trailing edge margins of the blades are connected to the rear spider by angles riveted to such blade portions and to the rear spider and leading edge margins of the blades are riveted to arms of the front spider.

United States Patent @191 Felker May 15, 1973 541 RADIAL AND AXIALAIRFLOW FAN 2,347,839 5 1944 Norris ..416/185 [76] Inventor: Samuel A.Felker, 10233 Green FOREIGN PATENTS OR APPLICATIONS Lane S.W., Tacoma,Wash. 98499 621,326 4/1949 Great Britain ..416/214 [22 Filed: Dec. 7,1970 [21] APPL No: 95,768 Primary ExaminerEverette A. Powell, Jr.

Attorney Robert W. Beach [52] U.S. Cl ..416/214, 416/186 [57] ABSTRACT[51] Int. Cl ..F04d 29/34 [58] Field of Search.....-. ..416/214, 243,185, f fi 6/186 179 182 132A 183 a y extending fan a es are secure tothe arms 0 front and rear portions spaced apart axially. A largeaperture in the central portion of the front spider ena- [56] ReferencesC'ted bles air to flow axially into a chamber between the UNITED STATESPATENTS front and rear spiderswhich opens radially outwardly I betweenthe root portions of the blades. Trailing edge 2,032,224 2/1936 Paton4l6/132 margins of the blades are connected to the rear spider 3,323,7116/1967 y? l UX by angles riveted to such blade portions and to the 1,01et al X rear pider and leading edge margins of the blades are 2,262,695l1/l941 Mueller ..416/93 riveted to arms of the from Spider. 2,347,8385/l944 Norris ..416/185 8 Claims, 12 Drawing Figures PATENTED MAY 151973 SHEET 2 OF 2 3 AMJH. A FHA 6 RADIAL AND AXIAL AIRFLOW FAN In thefan of the present invention a principal object is to provide a centralair chamber opening both radially outwardly between root portions of theblades and forwardly to enable air to flow axially into such air chamberand then generally radially outwardly, in addition to the axial flow ofair produced by the radially outer portions of the blades.

A further object is to provide strong and rugged blade-mountingstructure which is of open center and unobstructed root character, toenable air forward of the hub portion of the fan to flow through theblademounting structure with minimum turbulence.

Another object is to provide mounting structure for the fan blades whichis simple in character, yet which will support the fan blades securelyunder high blade loading with no substantial forward bending.

Another object is to provide a fan having unusually large air-movingability for its size.

Additional objects are quietness and elimination of air surges caused byhigh turbulence.

FIG. 1 is a rear elevation of a fan according to the present invention,and FIG. 2 is an edge elevation of such fan. FIG. 3 is a front elevationof the fan having parts broken away. FIG. 4 is an enlarged detailsection of a portion of the fan taken on line 4--4 of FIG. 1. FIG. 5 isa diametral transverse section through the fan on line 5 5 of FIG. 3.

FIG. 6 is a rear elevation of a modified type of fan, and FIG. 7 is anedge elevation of such fan. FIG. 8 is an enlarged detail section of aportion of the fan taken on line 8-8 of FIG. 6.

FIG. 9 is a front elevation of a further modified fan according to thepresent invention. FIG. 10 is a transverse diametral section throughsuch fan on line 10-10 of FIG. 9. FIGS. 11 and 12 are enlarged detailsections taken on line llll of FIG. 9, showing parts indifferentpositions.

The fan of the present invention is intended to be used primarily forautomotive purposes, specifically for drawing or forcing air through anengine-cooling radiator, although the fan can be used in a variety ofinstallations for producing a current of air. Such air current movespredominantly axially of the fan, but locally, at its central portion,the air moves first axially, then radially and then axially again,generally smoothly, instead of turbulent conditions predominating infront of the central portion of the fan.

The number of fan blades is not critical; from two to twelve or moreblades can be used. The representative fans shown in the drawings havesize blades. Each blade is cambered, preferably being of circulararcuate cross sections from root to tip. The transverse arc of eachblade preferably is less than 90. Also preferably the blade is taperedoutwardly as shown and has a rounded tip. It should be understood,however, that the particular profile and camber of the blade is notcritical for the present invention and can be selected according to the.

type of installation for which the fan is designed and its desiredoperating characteristics.

In the construction shown the fan blades are mounted to have a highangle of attack, such as approximately 45. Consequently, the blades aresupported so that their leading edges are located a substantial distanceahead of their tralling edges. To mount the blades in such fashion theirinner end portions are secured to two axially-spaced central plates,preferably in the form of spiders, without a solid hub. The front spider2 includes a ring portion and arms 3 projecting outward fromcircumferentially spaced portions of such ring portion to form throats3' between adjacent arms. One edge of each spider arm extendssubstantially tangentially of an inscribed circle passing through thethroats between the arms and the other edge of each arm extendsgenerally radially of the spider. Each spider arm projects radiallybeyond the inscribed circle through the throats for a radial distancegreater than half of the radius of such circle, as shown in FIG. 3. Theinner end portions of the blades project inward beyond the throats ofthe front spider into overlapping relationship with the spider ringportion. Such arms are secured to the inner end portions of the leadingedge margins of the blades by a plurality of spaced rivets 4 arranged ina radial row.

The rear spider 5 is connected to the front spider 2 by connecting pins6, such as bolts, extending through the front spider arms 3 and thecorresponding rear spider arms 7. Such corresponding front and rearspiders arms are disposed generally in registry axially of the fan andare mutually supported and held indefinitely spaced parallelrelationship by spacer sleeves 8 interposed between such spiders,through which the pins 6 connecting these spiders extend.

Because of the transverse curvature of the blades, their trailing edgemargins are disposed at a substantial angle to the plane of the rearspider 5. Consequently, the trailing edge margin of the blade isconnected to the rear spider by an angle connector. In the fan shown inFIGS. 1 to 5, inclusive, the spiders 2 and 5 are spaced apart a distanceless than the axial extent of the inner ends of the blades 1, andconsequently the flange 9 of the angle connector parallel to the rearspider 5 is secured by rivets 10 to the back of the rear spider. Theother flange 11 of each angle connector projects generally rearwardlyand is secured to the trailing edge margin of a blade by rivets 12. Asshown in FIG. 1, such flange extends along the major portion of thelength of the blade trailing edge to which it is connected.

For many installations, and particularly for automotive cooling airfans, the space in which the fan must be accommodated is limited.Disposition of the spiders 2 and 5 closer together than the axial extentof the blades, as indicated in FIG. 4 and 5 in particular, is thereforenecessary. The end of the drive shaft for the fan or a drive shaft bosscan project forward into an aperture 13 in the center of the rearspider. Holes 14 arranged in a circle around the hole 13 receive boltsfor anchoring the hub portion of the fan to the drive mechanism.

A large aperture 15 in the central portion of the front spider 2 opensinto the central chamber between the front spider 2 and the rear spider5 which is in communication with the inner ends 16 of the fan bladesthat are secured to the spiders. The width of such aperture should begreater than half of the minimum diameter of an inscribed circle definedby throats 3' of the front spider. Such central chamber opens radiallyoutward at a plurality of locations between the inner end portions ofadjacent blades.

Rotation of the fan blades about the rotative axis of the fan causes theouter portions of the fan blades to produce an axial flow of airrearward. The entire body of air forward of the fan tends to moverearwardly as a unit, but in conventional fans closed fan hub portionsblock rearward flow of air directly forward of such a hub portion, sothat the air cannot flow smoothly rearward but becomes turbulent andconsequently interferes with the axial rearward flow of air past theouter portions of these blades, which decreases the efficiently of thefan operation.

In the fan of the present invention the aperture through the centralportion of the front spider 2 enables air directly ahead of the fancenter to flow into the central chamber of the fan between the spiders 2and 5. The circumferential propulsive effect of the inner end portionsof the blades and the aspirating action of the air current flowingaxially through the radially outer portion of the fan induces air toflow radially outwardly from the central hub chamber to join the axialflow through the radially outward portion of the fan. Consequently, theaxial flow of air through the front spider aperture 15 into the centralchamber and flow of air radially outward from such chamber between theblade inner ends provides a definite flow pattern which minimizesturbulence both ahead of and behind the central portion of the fan andincreases both the capacity and efficiency of operation of the fan.

The blades 1 of the fan shown in FIGS. 6, 7 and 8 are essentially thesame as the blades of the fan shown in FIGS. 1 to 5, inclusive. In thisinstance again the front spider 17 has arms 18 to which the leadingmargins of the blades are secured by rivets 19. The arms 21 of the rearspider 20 are connected to the arms 18 of the front spider 17 by pins 21in a definitely spaced relationship established by the spacer sleeves 22between the spiders through which the pins 21 extend.

The spacing of the spiders 17 and 20 of the fan shown in FIGS. 6, 7 and8 is greater than the spacing of the front and rear spiders of the fanshown in FIGS. 1 to 5, and is substantially equal to the axial extent ofthe blade inner ends as shown in FIG. 8. The margins of the trailingedges of the inner blade ends are connected to the rear spider 20 byangle connectors having flanges 23 secured to the arms of the rearspider 20 by rivets 24. The forwardly projecting flanges 25 of the angleconnectors are secured to the trailing edge margins of the blade inneredge by rivets 26.

As described in connection with the fan shown in FIGS. 1 to 5, the rearspider 20 has a central aperture 27 arranged to receive the forward endof a fansupporting shaft or shaft boss. Fan-securing bolts can extendthrough the holes 28 arranged in a circular row around the centralaperture 27 to secure the fan to the driving mechanism. The front spider17 has a large central aperture 29 communicating with the chamberbetween the front spider 17 and the rear spider 20 through which boltsin holes 28 are accessible.

Because the chamber between the front spider 17 and the rear spider 20of the fan shown in FIGS. 6 to 8 is deeper axially than the chamberbetween the front spider 2 and the rear spider 5 of the fan shown inFIGS. 1 to 5, the flow of a given quantity of air through the hollowcentral chamber of FIGS. 6 to 8 will be slower, and it will not benecessary for the airflow entering the opening 29 to change direction soabruptly for flow outward through the openings between the inner ends ofthe blades. Consequently, the airflow ahead of the rear spider mountingportion of the fan shown in FIGS. 6 to 8 will be much greater and theturbulence resulting from meeting of the radially outward flow and theaxially rearward flow beyond the discharge openings from 4 the hollowcentral chamber will be less than in the fan of FIGS. 1 to 5.

The fan construction of FIGS. 9 to 12 is quite similar to that of thefan shown in FIGS. 6 to 8, including the rear spider 20 and itsconnection to the margins of the trailing edges of the blades by anangle connector 23,25 and rivets 24,26. In this instance, however, thefront spider 30 is not directly connected to the rear spider 20 by boltsas in the fan construction described above.

In the fan of FIGS. 9 to 12, inclusive, the front spider 30 has armsconnected to the margins of the inner end portions of the blade leadingedges by rivets 32 arranged in radial rows, as shown in FIG. 9. Sucharms 31 form throats 31 between them. The central portion of the spider30 has in it an aperture 33 communicating with the central chamberbetween the front spider 30 and the rear spider 20.

In this type of fan the blades 1 in relaxed condition will be cupped toestablish the minimum spacing between the front spider 30 and the rearspider 20, as illustrated in FIG. 11. As the rotative speed of the fanincreases the blade 1 will flex toward flattened contour,

as shown in FIG. 12, so that the front spider will move away from therear spider to some extent to increase the axial depth of the centralchamber between the front and rear spiders.

The operation of the fan shown in FIGS. 9 to 12, inclusive, is generallysimilar to the operation of the fans shown in FIGS. 1 to 5 and 6 to 8.In this instance, however, as the rotative speed of the fan increases toproduce a greater quantity and velocity of airflow, the front and rearspiders will move apart to increase the axial depth of the centralchamber and blade projected width at the same time that the flow throughsuch central chamber is increasing. Consequently, the tendency forturbulence to be produced in the central region of the fan will bereduced while airflow will be increased by such automatic enlargement ofthe central chamber into which the air flows axially through theaperture 33, and from which it flows radially between the inner endportions of the fan blades.

I claim:

1. A fan comprising a front plate, a rear plate spaced axially from saidfront plate, a plurality of radial fan blades bridging between saidfront plate and said rear plate, each of said blades being curvedtransversely to form an are between its leading edge and its trailingedge substantially less than degrees and to dispose the trailing portionof each blade at a substantial angle to said rear plate, meansconnecting the leading portion of each blade to said front plate, andmeans connecting said blade trailing portion to said rear plate, thecentral portions of said front plate and of said rear plate being spacedapart axially for providing a central chamber between said plates, saidfront plate having a central aperture therethrough enabling air to flowin an axial direction inwardly into said central chamber and saidcentral chamber opening generally radially outwardly between the innerend portions of said blades for discharge of air therefrom.

2. The fan defined in claim 1, in which the front plate is a spiderincluding a ring portion and circumferentially spaced arms radiatingfrom said ring portion, having throats therebetween and connected,respectively, so the leading edge margins of the blades, the inner endportions of the blades projecting inward beyond said throats intooverlapping relationship with said spider ring portion.

3. The fan defined in claim 1, and angle connectors each having a firstflange connected to the rear plate and a second flange projectinggenerally axially of the fan from said first flange and connected to theblade trailing portion.

4. The fan defined in claim 3, in which the second flange of each angleconnector projects rearwardly from the first flange of such connector.

5. The fan defined in claim 3, in which the second flange of each angleconnector projects forwardly from the first flange of such connector.

6. The fan defined in claim 1, in which the front plate and the rearplate are spiders including corresponding circumferentially spaced armsprojecting generally radially from the central portions of said spiders,said arms of the front plate spider and corresponding arms of the rearplate spider being disposed generally in registry axially of the fan,and spacer means independent of the blades connecting the correspondingregistering arms of said front plate spider and said rear plate spider,respectively, in definitely spaced relationship.

7. The fan defined in claim 3, in which the second flange of each angleconnector extends along a major portion of the length of the bladetrailing edge portion to which it is connected.

8. The fan defined in claim 6, and angle connectors each having a firstflange connected to a rear plate spider arm and a second flangeprojecting generally axially of the fan from said first flange andconnected to a blade trailing portion, the outer end portion of eachangle connector projecting generally radially outwardly to a location asubstantial distance beyond the outer end of the radiating arm of thefront plate spider corre sponding to the rear plate spider to which suchangle connector is connected.

1. A fan comprising a front plate, a rear plate spaced axially from saidfront plate, a plurality of radial fan blades bridging between saidfront plate and said rear plate, each of said blades being curvedtransversely to form an arc between its leading edge and its trailingedge substantially less than 180 degrees and to dispose the trailingportion of each blade at a substantial angle to said rear plate, meansconnecting the leading portion of each blade to said front plate, andmeans connecting said blade trailing portion to said rear plate, thecentral portions of said front plate and of said rear plate being spacedapart axially for providing a central chamber between said plates, saidfront plate having a central aperture therethrough enabling air to flowin an axial direction inwardly into said central chamber and saidcentral chamber opening generally radially outwardly between the innerend portions of said blades for discharge of air therefrom.
 2. The fandefined in claim 1, in which the front plate is a spider including aring portion and circumferentially spaced arms radiating from said ringportion, having throats therebetween and connected, respectively, so theleading edge margins of the blades, the inner end portions of the bladesprojecting inward beyond said throats into overlapping relationship withsaid spider ring portion.
 3. The fan defined in claim 1, and angleconnectors each having a first flange connected to the rear plate and asecond flange projecting generally axially of the fan from said firstflange and connected to the blade trailing portion.
 4. The fan definedin claim 3, in which the second flange of each angle connector projectsrearwardly from the first flange of such connector.
 5. The fan definedin claim 3, in which the second flange of each angle connector projectsforwardly from the first flange of such connector.
 6. The fan defined inclaim 1, in which the front plate and the rear plate are spidersincluding corresponding circumferentially spaced arms projectinggenerally radially from the central portionS of said spiders, said armsof the front plate spider and corresponding arms of the rear platespider being disposed generally in registry axially of the fan, andspacer means independent of the blades connecting the correspondingregistering arms of said front plate spider and said rear plate spider,respectively, in definitely spaced relationship.
 7. The fan defined inclaim 3, in which the second flange of each angle connector extendsalong a major portion of the length of the blade trailing edge portionto which it is connected.
 8. The fan defined in claim 6, and angleconnectors each having a first flange connected to a rear plate spiderarm and a second flange projecting generally axially of the fan fromsaid first flange and connected to a blade trailing portion, the outerend portion of each angle connector projecting generally radiallyoutwardly to a location a substantial distance beyond the outer end ofthe radiating arm of the front plate spider corresponding to the rearplate spider to which such angle connector is connected.